Smear bottom and sides of a 10″ cast-iron skillet with butter. Toss pecans, peaches, brown sugar, granulated sugar, lemon juice, garam masala, and salt in a large bowl to combine. Transfer to skillet and crumble topping, breaking up into large pieces, over filling.

Bake crisp until topping is golden brown and juices are thick and bubbling around the edges, 25–35 minutes.

Do Ahead

Crisp can be made 1 day ahead. Store lightly covered at room temperature.